将上下文菜单绑定到ListBox的Items集合 [英] Binding a context menu to a ListBox's Items collection

问题描述

我正在尝试为一个列表框创建一个上下文菜单，该菜单在列表框中显示元素。我可以使用以下XAML完成此操作：

I'm trying to create a context menu for a list box which displays elements in the context menu from the list box. I am able to accomplish this by using the following XAML:

<Window.Resources>        
    <ContextMenu x:Key="contextMenu" 
                 ItemsSource="{Binding Items, 
        RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListBox}}}" >
        <ContextMenu.ItemTemplate>
            <DataTemplate>
                <TextBlock Text="{Binding Content}"/>
            </DataTemplate>
        </ContextMenu.ItemTemplate>
    </ContextMenu>

    <Style TargetType="{x:Type ListBox}">
        <Setter Property="ContextMenu" Value="{StaticResource contextMenu}"/>            
    </Style>
</Window.Resources>

此功能非常适合一个列表框。但是，当我有第二个列表框时，上下文菜单将继续显示第一个列表框中的元素。换句话说，上下文菜单的ItemsSource不会更改。只有第一次打开上下文菜单时，才设置ItemsSource属性。例如：

This works great for one list box. However, when I have a second list box, the context menu keeps showing the elements from the first list box. In other words, the ItemsSource of the context menu does not change. Only the first time that the context menu is opened is the ItemsSource property set. For example:

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition/>
        <ColumnDefinition/>
    </Grid.ColumnDefinitions>

    <ListBox x:Name="first" >
        <ListBoxItem>First 1</ListBoxItem>
        <ListBoxItem>First 2</ListBoxItem>
        <ListBoxItem>First 3</ListBoxItem>
        <ListBoxItem>First 4</ListBoxItem>
        <ListBoxItem>First 5</ListBoxItem>
    </ListBox>
    <ListBox x:Name="second" Grid.Column="2" >
        <ListBoxItem>Second 1</ListBoxItem>
        <ListBoxItem>Second 2</ListBoxItem>
        <ListBoxItem>Second 3</ListBoxItem>
        <ListBoxItem>Second 4</ListBoxItem>
        <ListBoxItem>Second 5</ListBoxItem>
    </ListBox>    
</Grid>

我想在样式中设置上下文菜单，因为我有很多列表框实例，并且不想为每个列表框定义单独的上下文菜单。

I would like to set the context menu in a Style because I have many instances of a listbox and do not want to define a separate context menu for each listbox.

更新：
我终于想出了解决方法。我只需要绑定到PlacementTarget.Items并使用一个自相关的源，而不是使用一个查找祖先的相对源。

UPDATE: I finally figured out how to fix it. I just need to bind to the PlacementTarget.Items and using a self relative source instead of using a find ancestor relative source.

<ContextMenu x:Key="contextMenu" 
  ItemsSource="{Binding PlacementTarget.Items, 
  RelativeSource={RelativeSource Self}}" >

推荐答案

找到答案了，我只需要绑定到

Found the answer, I just need to bind to the PlacementTarget.Items and using a self relative source instead of using a find ancestor relative source.

<ContextMenu x:Key="contextMenu" 
  ItemsSource="{Binding PlacementTarget.Items, 
  RelativeSource={RelativeSource Self}}" >

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